ASC and ABS light goes on every now and then

[sshah261]

Hey guys, sorry there may already be a thread on this but I'm new to the forums. I recently bought a '97 e36 M3 and after about a month or so the ABS and ASC light would go on intermittently. As I am driving they turn on randomly but then if I turn the car off and back on the lights go off, but then again as I am driving they turn back on at some point. Any body have the same problem? First time around my mechanic came to the conclusion of a blown fuse, was fixed for about a week and started happening again. i live in chicago and its been crazy here without my traction control...i cant drive the car lol

[jayjaya29]

Do they turn on when you hit a bump? When you are on the brakes? Need more info.

[DrewSkii]

Same thing happens to me with my ABS. The light has turned on for me over bumps and when I press the brakes a little aggressively
Any ideas as to what could be causing this?

[scoobiedoo2029]

the brake travel sensor on the vacuum booster likes to break its solder joints, its not a cheap part new but you can repair it or you can find a used one cheap. theres a thread on it on m3forums about troubleshooting abs.

[sshah261]

They come on randomly throughout driving and also if I were to hit the brakes pretty hard...the lights (abs and asc) will turn on and stay on until I turn the car off. Then if I were to turn the car back on, put it into first, then the lights turn back on right away

[MMMGP]

http://forums.bimmerforums.com/forum...ch-ABS-DIY-Fix

[jhott66]

I know this is not a popular recommendation but the only way to fix your issue is to have the DTCs (diagnostic trouble code) read.
It could be a wheel speed sensor, a brake pedal switch, ABS controller, master cylinder travel sensor, any other failures in the ABS hydraulic/mechatronic system.
Get the codes, analyze the codes, fix the problem.

[scoobiedoo2029]

^ having a computer tell you whats wrong is cool, its very far from the only way to fix electronics


The definitive guide to self diagnosing your ABS/ASC light:
http://www.m3forum.net/m3forum/showthread.php?t=341672

[jhott66]

^ having a computer tell you whats wrong is cool, its very far from the only way to fix electronics


The definitive guide to self diagnosing your ABS/ASC light:
http://www.m3forum.net/m3forum/showthread.php?t=341672

I understand this and never said it was.
It is, though, by far the easiest and most efficient way to diagnose an electrical fault.
DTCs are set for a reason: to help diagnose electrical faults.

OP: I recommend you have the DTCs read and analyzed. It will save you hours and hours of your life. Otherwise you will be checking continuity across circuits until you blue.
It could be something as simple as the brake pedal switch or as expensive as the ABS controller.

[havasusteve1]

JHOTT66 makes a valid point. Another considerationn is to purchase your own Peake reader and pull codes yourself. The are fairly inexpensive and are very accurate. They are invaluable in the E39 and E60 world. It will allow YOU to diagnose tyhe issue then replace that part vs. the Stealers rolling the dice and choosing the most expensive solution.

Steve

[shogun]

having a computer tell you whats wrong is cool, its very far from the only way to fix electronics

The definitive guide to self diagnosing your ABS/ASC light:
[/B]http://www.m3forum.net/m3forum/showthread.php?t=341672

The pics in the m3forum net do not work anymore, I asked for the pics, but apparently they were removed by the thread opened and someone commented "WRXEATR was chased away from the forum a long time ago. Highly unlikely he'll ever return." Looks like he was not online there since around 2010.
Did anyone download the pics from there and can post them here?

[jhott66]

The pics in the m3forum net do not work anymore, I asked for the pics, but apparently they were removed by the thread opened and someone commented "WRXEATR was chased away from the forum a long time ago. Highly unlikely he'll ever return." Looks like he was not online there since around 2010.
Did anyone download the pics from there and can post them here?

The pics in that thread are not useful. The general content and process for going through the diagnosis is helpful for at least giving you a lesson on all the components interrelated in the system. The author of the thread got a lot of heat but it's generally useful. Just don't think you'll find your answer after a few minutes of poking with a multimeter.
Also, you have to be wary of the values the writer quotes, they are more often than not wrong.

Download the manual for your year and go through each step and check voltage and resistance across the terminals in the connector.
If I've written it once, I've written it 50 times: Go get the codes read from the ABS controller by a good tech. This will at the least set you in the correct direction. Otherwise you are just guessing.
Good luck.

[niemanj]

The pics in that thread are not useful. The general content and process for going through the diagnosis is helpful for at least giving you a lesson on all the components interrelated in the system. The author of the thread got a lot of heat but it's generally useful. Just don't think you'll find your answer after a few minutes of poking with a multimeter.
Also, you have to be wary of the values the writer quotes, they are more often than not wrong.

Download the manual for your year and go through each step and check voltage and resistance across the terminals in the connector.
If I've written it once, I've written it 50 times: Go get the codes read from the ABS controller by a good tech. This will at the least set you in the correct direction. Otherwise you are just guessing.
Good luck.

I'm going to give it a try, I'm OK to go to a shop and ask to read the codes but I'm not sure this is going to work as this is a build race car in which they removed the ABS computer and sensors. Original build date September 1994. It now has a M52b28 with a ZF trans but originally it was a M50b25 automatic. So I bought sensors and bought what I think should be the ABS computer. So I went through all the steps in the guide to troubleshooting ABS problems and it all came out OK but the issue seems to be the power to the connectors of the ABS computer. I measured the connector pins that should have power. I'm missing power on pin 3 and 33 which points to a relay problem. I replaced that but no go. Digging further I shorted the relay pins and got power on 3 and 33. So it seems the relay does not get activated. Testing the relay outside the car it clicks and does what it should do. So I'm down to a relay coil that does not get activated when I feed power to the car. So that points to a ground issue but the proper pins do have ground. I'm at a loss.